Vibratory compacting machine

ABSTRACT

A vibratory compacting machine has a machine frame, at least two masses which are spring mounted relative to each other and to the frame, and a vibration exciting mechanism which is arranged to cause the masses to vibrate in a push-pull sense with respect to each other, the arrangement being such that the vibrations are substantially balanced and relatively little stress is placed on the machine frame. The masses may all be compacting tools which are sprung from the machine frame and are arranged to impact the ground. Alternatively one of the masses may be a compensating mass which is spring mounted between the machine frame and the other mass which forms a compacting tool. In a modification of this latter arrangement the compensating mass has portions which are also arranged to impact the ground so that the compensating mass doubles as a compacting tool. In an alternative arrangement the sensitive parts of the machine are mounted on the machine frame which is separated from the compacting parts of the machine by a flexible coupling which is connected to the compacting parts at the center of gravity.

United States Patent [1 1 Vural et al.

[451 Sept. 30, 1975 VIBRATORY COMPACTING MACHINE [73] Assignee: KoehringGmbl-l BOMAG Division, Boppard, Germany 221 Filed: June 22,1973

2| Appl. No.: 372,621

[30] Foreign Application Priority Data June 24, 1972 Germany 2231023[52] US. Cl. 404/133 [51] Int. Cl. E01C 19/34 [58] Field of Search404/133, 114

[56] References Cited UNITED STATES PATENTS 2,084,983 6/1937 Baily404/133 2,636,719 4/1953 O'Connor 404/114 X 3,024,861 3/1962 Clynch404/133 X 3,283,677 11/1966 Uebel 404/133 X 3,834,827 9/1974 Linz404/133 FOREIGN PATENTS OR APPLICATIONS 483,501 4/1938 United Kingdom404/133 1,184,623 7/1959 France 404/133 Primary Exwniner-Nile C. Byers,Jr. Attorney, Agent, or Firm-Spencer & Kaye [57] ABSTRACT A vibratorycompacting machine has a machine frame, at least two masses which arespring mounted relative to each other and to the frame, and a vibrationexciting mechanism which is arranged to cause the masses to vibrate in apush-pull sense with respect to each other, the arrangement being suchthat the vibrations are substantially balanced and relatively littlestress is placed on the machine frame. The masses may all be compactingtools which are sprung from the machine frame and are arranged to impactthe ground. Alternatively one of the masses may be a compensating masswhich is spring mounted between the machine frame and the other masswhich forms a compacting tool. In a modification of this latterarrangement the compensating mass has portions which are also arrangedto impact the ground so that the compensating mass doubles as acompacting tool. In an alternative arrangement the sensitive parts ofthe machine are mounted on the machine frame which is separated from thecompacting parts of the machine by a flexible coupling which isconnected to the compacting parts at the center of gravity.

5 Claims, 8 Drawing Figures FIG.2

FIG. 1

b: E (o 5: E

FIG. 3

FIG. 5

FIG. 6

US. Patent Sept. 30,1975 Sheet20f2 3,909,148

FIG. 7

FIG. 8

1 VIBRATORY COMPACTING MACHINE I BACKGROUND OF THE INVENTION Thisinvention relates to vibratory compacting machines, which are mainlyused for compacting soil, of the kind comprising a machine frame, acompacting tool which is spring mounted relative to the frame, and avibration exciting mechanism for vibrating the compacting tool.

With vibratory compacting machines in general it is desirable to avoidthe transmission of vibrations from the compacting tool to the machineframe during operation. Such transmitted vibrations affect the stabilityof the machine frame as well as other parts carried by the frame, andfurthermore the vibrations are not pleasant for the machine operator whois either seated on the machine frame or is hand guiding the machinedepending on the type of machine being used. The type and extent ofstrain produced in the machine frame by such transmitted vibrationsdepends greatly on the form of vibration exciting mechanism used in themachine. Various forms of vibration exciting mechanism are known, suchas those providing vibration producing forces by means of massacceleration, those producing vibration producing forces by means ofelastic deformation, and those providing vibration producing forces bymeans of unbalanced centrifugal force generators, sometimes known asinertial force exciters. Also known are mechanisms which make use of amotor driven crank gear to provide the vibration producing forces.

With this latter type of mechanism, the vibration producing forces aretransmitted to the compacting tool through a spring, and tensile andcompressive stresses are produced alternately in the spring as a resultof the crank stroke. Although it is known to support the compacting tooland the vibration exciting mechanism from the machine frame by means ofsprings, satisfactory suppression of the transmission of vibration fromthe compacting tool to the machine frame during use has not yet beenachieved. This is evident from the fact that vibratory compactingmachines with a crank type of vibration exciting mechanism areinvariably made as light hand guided machines having a dead weight of nomore 100 kilograms. With machines having a dead weight greater than thisthe vibrations transmitted to the machine frame during operation arevirtually uncontrollable.

SUMMARY OF THE INVENTION According to the present invention, suchoperationally transmitted vibrations in vibratory compacting machines ofthe kind described can be very much reduced if: a compensating mass isspring mounted between the machine frame and the compacting tool, andthe vibration exciting mechanism is arranged to vibrate the compensatingmass and the compacting tool in a push-pull sense; or there are at leasttwo compacting tools spring mounted from the machine frame, and thevibration exciting mechanism is arranged to vibrate the tools in apush-pull sense; or the machine is mobile, having a tractive unit and acompactor unit including the compacting tool, the vibration excitingmechanism cm prises exciter means carried by the compactor unit and apower source for the exciter means carried by the tractive unit, andthere is a connecting member between the tractive unit and the compactorunit, the

member being connected to the compactor unit substantially at its centerof gravity.

By arranging that in a vibratory compacting machine of the kinddescribed there are at least two masses, at least one of which is acompacting tool, which are spring mounted relative to each other and tothe machine frame, and that the vibration exciting mechanism causes themasses to vibrate in a push-pull sense, the push-pull vibrations may besubstantially balanced so that little vibration is transmitted to themachine frame. Virtually total compensation occurs when the massesvibrate in a push-pull sense with equal products of mass and stroke.

In a particular form of machine of this construction, a compacting toolis spring mounted from a compensating mass which in turn is springmounted from the machine frame, and the vibration exciting mechanism isarranged to vibrate the compacting tool and the compensating mass in apush-pull sense, the compensating mass being arranged to double as asecond compacting tool which in use acts on the surface to be compacted.

Alternatively, the transmission of vibrations to the sensitive parts ofa vibratory compacting machine is reduced by separating the sensitiveparts from the compacting part of the machine by a flexible coupling bywhich power is delivered to the vibration exciter in the compactingpart, and by which the compacting part may also be moved.

BRIEF DESCRIPTION OF THE DRAWING Various examples of vibratorycompacting machines in accordance with the present invention will now bedescribed briefly with reference to the accompanying diagrammaticdrawings, in which FIG. 1 illustrates a first example having a singlecompacting tool;

FIG. 2 illustrates a second example which is similar to the first exceptthat the compacting tool is arranged to execute oscillatory vibrationsinstead of linear vibrations;

FIG. 3 illustrates a third example having two compacting tools, one ofwhich doubles as a compensating mass;

FIG. 4 illustrates a fourth example having three compacting tools:

FIGS. 5 and 6 together illustrate a fifth example which is similar tothe fourth except that the compacting tools are arranged to executeoscillatory vibrations instead of linear vibrations;

FIG. 7 illustrates a self-propelled machine which is otherwise similarto the example of FIGS. 5 and 6; and,

FIG. 8 illustrates a seventh example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIG.1, a compensating mass 2 is spring mounted between a machine frame 1 anda compacting tool 3 by means of springs 4 acting between the frame 1 andthe mass 2, and further springs 5 acting between the mass 2 and the tool3. A crank type of vibration exciting mechanism 21 may be housed in thecompensating mass 2 with the crank arranged to act on the compactingtool 3 through a spring 22. In operation, the vibration excitingmechanism sets the compensation mass 2 and the compacting tool 3vibrating linearly in opposition to each other, that is in a push-pullsense, as indicated by the arrows 6. The stiffness of the springs 4 issuch that their resistance to the motion of the compensating mass 2 islower, and conse-. quently the vibrations of the compacting tool 3 andof the compensating mass 2 will not be transmitted to the machine frame1 to any great extent.

This is also the case in the second example, represented in FIG. 2,where the vibration exciting mechanism causes the compacting tool 3 andthe compensation mass 2 to vibrate in an oscillatory fashion, asindicated by arrows 7, eachpivoting about its own axis 8 so thatadjacent ends move alternately towards and away from each other as shownin FIG. 2..

In the third example, shown in FIG. 3, the arrangement and operation issimilar to that of the first example shown in FIG. 1 except that thecompensating mass 9 which is spring mounted from the machine frame is ofinverted U-shape and straddles the compacting tool 10 which is supportedfrom the mass 9 by springs 11. The free ends of the mass 9 are arrangedto contact the ground on opposite sides of the compacting tool 10, andhence the compensating mass 9 also acts as a second compacting tool.

As with the example shown in FIG. I, the example of FIG. 3 forms a threemass oscillation system (compris ing the machine frame, the compensatingmass, and the compacting tool), and undesirable stresses placed on themachine frame by operational vibrations can be.

avoided by appropriate selection of the masses of the members 9 and Iand arrangements of their supporting springs. A machine having the basicconstruction shown in FIG. 3 may also be made in which the masses 9 andare arranged to execute oscillatory vibrations.

In the two examples illustrated in FIGS. 4, 5 and 6, each of threecompacting tools 12, 13, and 14- are supported side by side from amachine frame by springs 15.

The two outer tools 12 and 14 are similar to each other and togetherhave a mass equal to that of the center tool 13. The machines areprovided with vibration exciting mechanisms which generate vibrationproducing forces by means of elastic deformations and which are arrangedto vibrate the compacting tools 12 and 14 in the same mode as each otherand to vibrate the other tool 13 with the same frequency as the tools 12and 14 but 180 out of phase, i.e., in a push-pull sense with the tools12 and 14. In the example of FIG. 4 the compacting tools are arranged tovibrate linearly, whereas in the example of FIGS. 5 and 6 the tools arearranged to vibrate in an oscillatory fashion about a common axis 16.

In these two examples substantial compensation of the reaction forcesfrom the vibration exciting mechanism which is carried by the machineframe is achieved and it thus becomes possible and practical toconstruct a similar machine which is mobile with a built in drivingmotor. Such a machine is illustrated diagrammatically in FIG. 7. In theexample shown the three compacting tools are arranged to vibrate in anoscillatory mode about an axis 16, although it is just as feasible toarrange for the tools to vibrate linearly as in the example of FIG. 4.

In the example shown in FIG. 8 the compacting tool and compensation massare not mounted directly below the machine frame, but form a separateunit which is pivotally connected at its center of gravity to a couplingmember 19 which connects the unit to the machine frame 18 which isconstructed as a mobile tractive unit for propelling the compactingtools. The

compacting tools are arranged in a similar fashion to those in theexample ofFIG. 3 andcarry a vibration exare in the form of plates orbeams, although they may instead be inthe form of rollers. Similarly,the springs illustrated between the machine frame, the compensatingmass, and the compacting tools may be simple coil springs or any othersuitable spring systems.

We claim: 1. A vibratory compacting machine comprising: a machine frame;a compacting tool; a compensating mass; spring means having a low springstiffness connected between said frame and said compensating mass forsupporting said mass from said frame; means connected to support saidtool from said mass;

and oscillating vibration means connected between, and

to each of said compacting tool and said compensating mass for causingsaid mass and said tool to vibrate in phase opposition whereby nomorethan a small portion of such vibrations is transmitted to said frame.

2. An arrangement as defined in claim 1 whereinsaid compensating massconstitutes a second compacting tool of inverted U-shape, straddlingsaid first-recited compacting tool and arranged to act on the samesurface as the first-recited compacting tool.

3. A vibratory compacting machine comprising: a

machine frame;

a pair of first similar compacting tools;

a second compacting tool disposed between said first tools and equal inmass to the sum of the masses of said first tools;

spring means supporting each said tool from said frame; and

oscillating vibration means connected between said frame and each ofsaid tools for vibrating said first tools in unison with one another andin phase opposition to said second tool so that no more than a smallportion of the vibrations is transmitted to said frame.

4. An arrangement as defined in claim 3 where said frame is atransportable vehicle.

5. A vibratory compacting machine comprising:

a machine frame in the form of a tractive unit;

a compactor unit having first and second compacting tools and springmeans connected between said tools;

oscillating vibration means connected between, and to each of, saidtools for vibrating said tools in phase opposition;

flexible coupling means connected between said tractive unit and saidcompactor unit and connected for delivering operating power to saidvibration means, said coupling means being connected to said compactorunit substantially at the center of gravity thereof.

1. A vibratory compacting machine comprising: a machine frame; acompacting tool; a compensating mass; spring means having a low springstiffness connected between said frame and said compensating mass forsupporting said mass from said frame; means connected to support saidtool from said mass; and oscillating vibration means connected between,and to each of said compacting tool and said compensating mass forcausing said mass and said tool to vibrate in phase opposition wherebyno more than a small portion of such vibrations is transmitted to saidframe.
 2. An arrangement as defined in claim 1 wherein said compensatingmass constitutes a second compacting tool of inverted U-shape,straddling said first-recited compacting tool and arranged to act on thesame surface as the first-recited compacting tool.
 3. A vibratorycompacting machine comprising: a machine frame; a pair of first similarcompacting tools; a second compacting tool disposed between said firsttools and equal in mass to the sum of the masses of said first tools;spring means supporting each said tool from said frame; and oscillatingvibration means connected between said frame and each of said tools forvibrating said first tools in unison with one another and in phaseopposition to said second tool so that no more than a small portion ofthe vibrations is transmitted to said frame.
 4. An arrangement asdefined in claim 3 where said frame is a transportable vehicle.
 5. Avibratory compacting machine comprising: a machine frame in the form ofa tractive unit; a compactor unit having first and second compactingtools and spring means connected between said tools; oscillatingvibration means connected between, and to each of, said tools forvibrating said tools in phase opposition; flexible coupling meansconnected between said tractive unit and said compactor unit andconnected for delivering operating power to said vibration means, saidcoupling means being connected to said compactor unit substantially atthe center of gravity thereof.